Keyframe: New implementation calculating values ondemand

- GetValue() calculates the value at the given position now ondemand,
  without caching values as previously.  First, it uses binary search
  to find the segment (start and end point) containing the given
  position.  Constant and linear interpolation are straightforward,
  bezier curves are calculating by binary search between the end
  points until a point on the curve is found with a X coordinate close
  enough to the given position. That points Y coordinate is returned.

- IsIncreasing(), GetRepeatFraction(), GetDelta() use GetValue()
  instead of accessing the (removed) Values vector.

- Removed now unused private functions, and the unused public
  Process().

First test results show good performance improvements for the
"rendering case" (setting up the keyframe points at once, then getting
all values) and drastic performance improvements for the "preview
case" (changing keyframe points, mixed with getting values).

Author: musteresel

include/KeyFrame.h

@@ -63,25 +63,7 @@ namespace openshot {
 	 */
 	class Keyframe {
 	private:
-		bool needs_update;
-		double FactorialLookup[4];
 		std::vector<Point> Points;			///< Vector of all Points
-		std::vector<Coordinate> Values;		///< Vector of all Values (i.e. the processed coordinates from the curve)
-
-		// Process an individual segment
-		void ProcessSegment(int Segment, Point p1, Point p2);
-
-		// create lookup table for fast factorial calculation
-		void CreateFactorialTable();
-
-		// Get a factorial for a coordinate
-		double Factorial(int64_t n);
-
-		// Calculate the factorial function for Bernstein basis
-		double Ni(int64_t n, int64_t i);
-
-		// Calculate Bernstein Basis
-		double Bernstein(int64_t n, int64_t i, double t);
 
 	public:
 
@@ -155,14 +137,6 @@ namespace openshot {
 		void SetJson(std::string value); ///< Load JSON string into this object
 		void SetJsonValue(Json::Value root); ///< Load Json::JsonValue into this object
 
-		/**
-		 * @brief Calculate all of the values for this keyframe.
-		 *
-		 * This clears any existing data in the "values" vector.  This method is automatically called
-		 * by AddPoint(), so you don't typically need to call this method.
-		 */
-		void Process();
-
 		/// Remove a point by matching a coordinate
 		void RemovePoint(Point p);